Conventionally, gas sensors that employ a solid electrolyte such as stabilized zirconia have been used as, for example, a sensor for sensing the concentration of oxygen contained in the exhaust gas from an on-vehicle engine. Moreover, various techniques have been proposed for eliminating sensing errors of these gas sensors.
For example, there has been known a technique of acquiring a sensor output value under a condition where a fuel cut is performed in an engine and calculating, as an output correction value, a deviation of the sensor output value based on a comparison between the sensor output value and a known reference output value in an atmospheric air condition (see, for example, Patent Document 1). In this case, a correction gain is calculated using the output correction value (atmospheric air output error) calculated in an atmospheric air correction process, and a correction of the sensor output value is performed using the correction gain when the air/fuel ratio is deviated from the stoichiometric ratio (theoretical air/fuel ratio).